Different functions of a motor vehicle roof are ensured in motor vehicles by means of roof modules. The motor vehicle body is often specifically designed to accommodate roof modules. The rigidity of the motor vehicle roof is ensured by means of a roof module frame, although a variety of functions is fulfilled. The roof module frames, for the most part, are connected to the body by means of adhesive bonds with the result that the body has to provide corresponding adhesive joints. The firmness of the adhesive bond used here does not generally equal that of a laser-soldered connection. Laser-soldered connections are often used in conventional roofs, wherein the outer skin of the roof is laser-soldered to the body. Although laser-soldered roofs do not have any roof module frames, they do mostly have one to three cross beams to ensure rigidity. The body must then be designed to accommodate the roof cross members. With bonded roof modules there is, in principle, the danger that the bond seam between the roof module frame and the body will break and that the roof module will break away from the motor vehicle. Breaking away of the roof must, however, be avoided, since then the overall rigidity of the passenger cabin decreases considerably and its properties in the case of deformation caused by an accident are impaired considerably. To prevent the roof module from breaking away and thus reducing the solidity of the passenger cabin in the event of an accident, it is known from the German published patent application DE 102 54 773 A1 to provide a retaining element on the roof module, into which the lateral roof frame of the motor vehicle body plunges in the event of a side impact and prevents the roof module from breaking away. Attaching the retaining element to the roof module is, however, labor-intensive. Moreover, the retaining elements impede the use of a roof module frame which is required to provide reinforcement. In addition, an increase in the flexibility of the use of the body would be desirable in the sense that the body, irrespective of whether a roof module or a conventional roof is to be used, is already fixed when the motor vehicle is ordered. Up to now, the bodies have been specifically designed for the use of conventional roofs or roof modules, so that the bodyshell work can only begin when the motor vehicle is ordered.